how to implement insert sort using c

insert_sort.c

#include <stdio.h>

int main() {
  int arr[] = {1, 8, 9, 4, 8, 7, 2, 3, 4, 90, 34};
  int len = sizeof(arr) / sizeof(arr[0]);
  int i;
  for(i = 1; i < len - 1; i++) {
    int key = arr[i];
    int j = i - 1;
    while(arr[j] > key && j >=0) {
      arr[j + 1] = arr[j];
      j--;
    }
    arr[j+1] = key;
  }

  for(i = 0; i < len - 1; i++)
    printf("%d ", arr[i]);
    printf("\n");
  
}